RESUMO
To study the fibrogenic action of ethanol in vitro we used a co-culture system of freshly isolated hepatocytes and a liver stellate cell line (CFSC-2G) developed in our laboratory. Our results show that in this co-culture system ethanol induces the expression of alpha 1(I) procollagen mRNA in a dose- and time-dependent manner. This effect of ethanol was due to its metabolism by alcohol dehydrogenase since 4-methylpyrazole prevented the ethanol-mediated increase in alpha 1(I) procollagen mRNA. Ethanol was more efficient than acetaldehyde in inducing alpha 1(I) procollagen mRNA expression and its effect was protein synthesis-independent. Transfection of either hepatocytes or liver stellate cells with a reporter gene, chloramphenicol acetyl transferase (CAT), driven by 3700 bp of the mouse alpha 1(I) procollagen promoter demonstrated that only LSC expressed significant CAT activity and that this activity was enhanced by ethanol. Overall, our results suggest that this co-culture system is a useful model to study alcohol-induced fibrogenesis in vitro and that mechanisms other than acetaldehyde formation may also play an important role in alcohol-induced fibrogenesis.
Assuntos
Etanol/farmacologia , Fígado/efeitos dos fármacos , Pró-Colágeno/genética , Acetaldeído/farmacologia , Animais , Células Cultivadas , Fibronectinas/genética , Fomepizol , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Fígado/citologia , Fígado/metabolismo , Masculino , Pirazóis/farmacologia , RNA Mensageiro/genética , Ratos , Ratos Sprague-Dawley , Transcrição Gênica/efeitos dos fármacosRESUMO
1. The present study was undertaken to determine if the platelet monoamine oxidase (MAO) activity of children with childhood-onset Pervasive Developmental Disorders (PDD), atypical PDD and autistic children differs from MAO of normal children of the same age. 2. The kinetic parameters of MAO activity (Km and Vmax for kynuramine as substrate in 100 mM sodium phosphate buffer, pH 7.4 at 37 degrees C) were determined for platelets from autistic (N = 6), childhood onset PDD (N = 6) and atypical PDD (N = 6) children and 14 controls aged 6-10 years. 3. PDD children had significantly lower Km (4.41 +/- 0.26 vs 5.30 +/- 0.23 microM) and Vmax (16.77 +/- 1.56 vs 22.15 +/- 2.16 nmol h-1 mg protein-1) than control children. The reduction in Vmax was demonstrable in MAO activity measured with 100 microM substrate (14.93 +/- 1.13 vs 20.96 +/- 2.10 nmol h-1 mg-1). 4. These data show that childhood-onset PDD patients, in which the syndrome was complete, presented the lowest levels of platelet MAO activity.
